1. Technical Field
The present invention relates to armatures for rotating electric machines.
2. Description of Related Art
There are known armatures for rotating electric machines which include an armature core and an armature coil. The armature core includes an annular main body and a plurality of teeth each extending radially inward from the main body and spaced from one another in the circumferential direction of the main body. The armature coil is arranged between the teeth of the armature coil.
For example, Japanese Patent Application Publication No. JP2012165630A discloses an armature, in which each of the teeth of the armature core has a protruding part formed at a distal end of the tooth so as to be circumferentially centered at the distal end and a pair of oblique parts formed respectively on opposite circumferential sides of the protruding part. Consequently, with the oblique parts of the teeth of the armature core, it is possible to retain the armature coil in position between the teeth of the armature core, thereby preventing the armature coil from being detached from the teeth.
However, in the armature disclosed in the above patent document, for each of the teeth of the armature core, the oblique parts of the tooth are configured to extend straight parallel to the protruding part of the tooth before the armature coil is arranged between the teeth of the armature core. Further, after the arrangement of the armature coil, the oblique parts are bent respectively in opposite circumferential directions away from the protruding part, thereby being deformed to extend obliquely with respect to the protruding part. Moreover, the oblique parts are also configured to have a constant width from the proximal end to the distal end thereof. Therefore, during the bending of the oblique parts, only proximal end portions of the oblique parts are locally deformed. Consequently, after the bending of the oblique parts, tensile or compressive stress may reside in the proximal end portions of the oblique parts, thereby deteriorating the magnetic properties of the oblique parts. Moreover, the oblique parts may be damaged due to concentration of the tensile or compressive stress on the proximal end portions.
To solve the above problem, the patent document further discloses examples of providing stress relaxation parts in the form of a cut at the proximal ends of the oblique parts, thereby relaxing the residual stress in the proximal end portions of the oblique parts (see FIGS. 8-11 of the patent document). However, with the stress relaxation parts provided at the proximal ends, the width of the oblique parts at the proximal ends is accordingly reduced. Consequently, it may become difficult for magnetic flux to flow through the proximal ends of the oblique parts, thereby lowering the performance of the rotating electric machine.